The normal menstrual cycle is around 22-35 days, so it is normal to have a delayed or early menstruation for 7 days or less. However, if it is more than 7 days or more than 7 days, either the delay or advance may be caused by endocrine disorder, or stressful work life or examinations, or change of geography, business trip, etc., which can cause delayed menstruation. Therefore, if there is a delay in menstruation, we should actively look for the cause. If it is an occasional early or delayed period, the next period will be normal again and we can temporarily ignore it and observe it. However, if the period is often delayed or is 7 days or more early, oral medication should be given to adjust the menstrual cycle according to the test results.